1. Field of the Invention
The present invention relates to a positive resist composition that undergoes reaction by irradiation with actinic ray or radiation to change properties, and a pattern formation method using the positive resist composition. More particularly, it relates to a positive resist composition used in production steps of semiconductors such as IC, production of circuit substrates such as a liquid crystal or a thermal head, other photofabrication steps, lithographic printing plates, and acid-curing compositions, and a pattern formation method using the positive resist composition.
2. Description of the Related Art
Chemically amplified resist compositions are a pattern forming material that forms an acid on an exposed area by irradiation with actinic ray such as far ultraviolet ray, or radiation, changing solubility to a developer between the exposed area by actinic ray or radiation and a non-exposed area by a reaction using the acid as a catalyst, and forming a pattern on a substrate.
Where KrF excimer laser is used as an exposure light source, a resin comprising a poly(hydroxystyrene) showing small absorption at 248 nm region as a basic skeleton is mainly used. Therefore, a pattern having high sensitivity and high resolution and being good is formed, and a good system is obtained as compared with the conventional naphthoquinone diazide/novolac resin system.
On the other hand, where light source having further short wavelength, for example, ArF excimer laser (193 nm) is used as an exposure light source, a compound having an aromatic group substantially shows large absorption at 193 nm region, and thus even the above chemically amplified system was not yet sufficient.
For this reason, a resist for ArF excimer laser containing a resin having an alicyclic hydrocarbon structure has been developing.
Various improvements are being made on an acid-decomposable resin that is a main constituent of a chemically amplified resin composition. For example, JP-A-2004-53822 discloses an acid-decomposable resin having a specific methacrylic repeating unit.
However, additionally, it is desired to enable line edge roughness (LER), exposure latitude (EL), PEB temperature dependency and pattern collapse to achieve together in high dimension.